---

<?php
$row = 4;
$col = 4;

$dx = [2, 2, -2, -2, 1, 1, -1 ,-1];
$dx = [1, -1, 1, -1, 2, -2, 2 ,-2];

for ($i = 0; $i < 8; $i++) {
    $newRow = $row + $dx[$i];
    $newCol = $col + $dy[$i];

    if ($newRow >= 1 && $newRow <= 8 && $newCol >= 1 && $newCol <= 8) {
        echo "Ход: ($newRow, $newCol)\n";
    }
}


//2 

$count = 0;

for ($i = 0; $i <= 999999; $i++) {
    $ticket = str_pad($i, 6, "0", STR_PAD_LEFT);

    $sum1 = $ticket[0] + $ticket[1] + $ticket[2];
    $sum2 = $ticket[3] + $ticket[4] + $ticket[5];

    if ($sum1 == $sum2) {
        $count++;
    }
}

echo "Количество счастливых билетов: $count\n";

//3

$a = 0;
$b = 1;

for ($i; $i <= 20; $i++) {
    if ($a % 3 == 0) {
        echo $a . "\n";
    }

    $next = $a + $b;
    $a = $b;
    $b = $next;
}

//4

$n = 5;

for ($i = 1; $i <= $n; $i++) {
    for ($s = 1; $s <= $i; $s++) {
        echo " ";
    }

    if ($i % 2 == 0) {
        echo "##";
    } else {
        echo "#";
    }
    echo "\n";
}

//5

$num = 97;
$isPrime = true;

for ($i = 2; $i <= sqrt($num); $i++) {
    if ($num % $i == 0) {
        $isPrime = false;
        break; 
    }
}

if ($isPrime) {
    echo "$num - Простое число\n"; 
} else {
    echo "$num - не простое число"
}